HP LaserJet 9040.9050 Multifunction Printer series - Manual (Page 143)

ENWW Clearing jams 139
4 Turn the small green knob at the top of the stapler unit clockwise until the staple cartridge
moves to the left of the stapler unit.
CAUTION The blue dot must appear in the window of the stapler unit before you remove the staple cartridge.
If you try to remove the staple cartridge before the blue dot appears in the window, you could
damage the finisher.
5 Remove the staple cartridge by squeezing the blue tabs together.
6 Pull up on the lever labeled with a green dot.